<html>

<table width=100%><tr>
    <td align=left> <a href="definition.html">&lt;- Definition</a></td>
    <td align=right><a href="build.html">Download and Install -&gt;</a></td>
</tr></table>
<hr>

<h2>Introduction</h2>

  <p>
  <i>osgEphemeris</i> provides the virtual environment for the sky, sun, moon, 
  planets and stars to be used with visualization applications using 
  <a href=http://www.openscenegraph.org> OpenSceneGraph</a>.  When using 
  <i>osgEphemeris</i>, the user provides the software with <b>Latitude</b>, 
  <b>Longitude</b>, <b>Date</b> and <b>Time</b>, and the software will provide
  a ground (or near-ground) view of the sky with the sun, moon, planets, and
  stars all positioned with reasonable accuracy.  

  <p>
  Note that <i>osgEphemeris</i> is intended for ground based visualization and
  does not extend to space flight or accurate representation of heavenly body 
  positioning other than for a view that is on or near the ground.  <i>Near</i>
  means within 40,000 feet of the ground, or so.  Altitudes are taken into 
  consideration and distance above horizon for heavenly bodies, but loose accuracy
  the higher the vantage point.

  <p>
  The software is provided for use in two methods: as a C++ API, or as a .osg
  file format, using OpenSceneGraph <i>Node Kit</i> methodology, which allows
  the definition of the EphemerisModel class to be defined in a <i>.osg</i>
  file (see section on <i>.OSG File Directives</i>).  This document
  will demonstrate how to use the osgEphemeris software, how to integrate it
  into your application and how to control its parameters.

  <p>
  Familiarity with OpenSceneGraph C++ API and OpenSceneGraph utility programs,
  such as <b>osgviewer</b> are assumed.
<hr>
<table width=100%><tr>
    <td align=left> <a href="definition.html">&lt;- Definition</a></td>
    <td align=right><a href="build.html">Download and Install -&gt;</a></td>
</tr></table>

</html>
